Chris - now you're starting to no longer make sense. It's irrelevant if it's on OS or an app issue. There are problems with certain Macs, OSX 10.6.8 and FCPX - we know that, Apple knows that and if it was real easy to fix, I am sure they would have by now. On my one machine that has the crash problems, I cannot upgrade to a newer OS or I'd have to uprage our SAN software too. If the SAN wasn't the issue, I'd upgrade to Mountain Lion in a heartbeat. It's a no brainer. I am running Mountain Lion on my MacBook Pro with FCPX and it works flawlessly and it's really fast.
What you label as "iOS junk" is actually the real strength of the new OS. I am talking about the OS engine you cannot see., not the interface gimmicks. FCPX no longer uses quicktime as its media engine, but AV foundation (which also runs on iPads and iPhones). AV foundation is the reason why FCPX does things so much faster, why it allows you to edit H.264 footage natively and it's all there built-into the OS. That gives FCPX a real advantage over other NLE's that have to be cross-platform. AV foundation wasn't 100% implemented until Lion.
Lion had some clunkie issues, but Mountain Lion is rock solid, IMHO. Unless you have hardware that's too old, or compatibility issues (as I do on that MacPro) there is absolutely ZERO reason not to upgrade for FPCX.